Fluid actuated power hammers



June 5, 1956 N. s. JOHNSON 2,748,751

FLUID ACTUATED POWER HAMMERS Filed Oct. 16, 1953 2 Sheets-Sheet l I w -f. Iii- :2.

22 IN V EN TOR. ibe/mam JoH/vso/v.

- ATTO/P/Vfii June 5, 1956 N. s. JOHNSON 2,748,751

FLUID ACTUATED POWER HAMMERS Filed Oct. 16, 1955 2 Sheets-Sheet 2 IN V EN TOR. NORMA 1v JOHNSON.

United States Patent FLUID ACTUATED POWER HAMlVlERS Norman S. Johnson, New York, N. Y., assignor to Raymond Concrete Pile Company, New York, N. Y., a corporation of New Jersey Application October 16, 1953, Serial No. 386,646

6 Claims. (Cl. 121-25) This invention relates to an improved type of diiferential piston, power hammer having slide valve means located directly in the piston thereof. This type of hammer is particularly adapted, among other possibilities, for use in the driving of piles and the like.

Dififerential hammers of the general type disclosed in United States Patent to E. A. Smith No. 2,598,455 granted May 27, 1952, have various advantages in the pile driving field. In such type hammers, however, the valves, valve passages and valve actuating means such as levers and cams are mounted either outside the hammer cylinder or within the cylinder walls. Due to the fact that such hammers utilize the differential piston principle, these valve assemblies are necessarily somewhat complicated and, when located on the outside of the cylinder, increase the overall outer diameter thereof appreciably. This tends to make the hammer cumbersome when working in confined qua-rters suchas when it is desired to drive a pile closely adjacent to awall. On the other hand, when an attempt is made to locate the valve passages and valve parts within the cylinder walls themselves, difficulties and expense of construction are enhanced: Moreover, since power hammers of this type must necessarily be subjected to severe strain: and: shock, the'numerous moving and interactingparts in: these previous valve assemblies involved the possibility of breakdown difficulties.

The present invention contemplates a difierential .pistonpower hammer which employs a steam operating cycle the same as that of the hammer disclosed in PatentNo. 2,598,455, but which embodies a sliding valve: assembly carriedentirely' by the differential piston itself. This results-in a very simple design involving: the use-of a minimumnumber of parts; since the entire valve assembly is self-containedin' the piston. Such an arrangement providesa very compact hammer. No projections of any kind whatsoever are necessary on: the outside of the cylinder. Moreover, the upper cylinder which receives the larger portionof the difierential piston; is free of. any steam passagestherein and as a result. the whole. power hammercanbe-m-ade of minimum outside dimensions; As alreadynoted, this is avery great advantage wheni t is desired to use the hammer in; confined spaces;

Theinvention further contemplates a design wherein the piston and rammay be integral; Since such a con'- st'ruetion. the only loose parts are the valves themselves, the result is a very compact and. durable hammer which can withstand the most severe shock: with a minimum-of resultingbreak-down'.

Further objects,.features and advantages of the invention hereofi will appear from the detailed description given below; taken in connection with the accompanying drawings which. form a part of this specification a'nd il'- lustrate by way of example, preferred embodiments-of the invention;

In thedrawings:v r

Fig. 1 is a vertical section-view of the difierential liammer showing the position of one type of sliding valve assembly at the downward end of the power stroke of the hammer;

Fig. 2 is a vertical section view of the differential hammer showing the position of the sliding valve assembly of Fig. 1 at the end of the upstroke of the hammer;

Fig. 3 is an enlarged fragmentary perspective View, showing one of the spring actuated friction rings referred to below, in gripping relation with a valve tube;

Fig. 4 is a view similar to Fig. 1 but showing a modified type of sliding valve assembly; and I Fig. 5 is a view similar to Fig. 2 but showing the modified valve assembly of Fig. 4.

Referring now in more detail to the drawings and particularly to Figs. 1 and 2, the embodiment of the invention therein disclosed comprises a hammer body 10, which is integrally bored from top to bottom so as to form an upper cylinder 11 of relatively large diameter having an internal, annular shoulder 12 at its lower extremity and a lower cylinder 13 of smaller diameter. The cylinder 11 is closed at its upper end by means of cylinder head 14 which is secured to the hammer body in any suitable fashion. This cylinder head is provided exteriorly with sheaves 15 so that the hammer may be suspended on cables 15' in operative position over the piling or core which is to be driven. Located in operative position within the bore of this hammer body 10, is a combined diiferential piston and ram assembly '16, comprising a relatively large diameter piston 17 disposed in the upper cylinder 11, a piston rod portion 18 of reduced diameter integral with said piston 17 and extending into the lower cylinder 13, and including a piston portion 20 having a plurality of piston rings 19. The pistonrod 18 extends beyond this smaller piston portion and. terminates in an impact surface 21 which is designed to deliver hammer blows to a cap block assembly 22 of the type disclosed in said U. S. Patent, No. 2,598,455 among others. This cap block assembly 22 is adapted to rest. on the upper end of the piling or'core which is to be driven and extend up into the lower end to cylinder 13 in alignment with piston rod 1%. The large piston 17 and piston rod 18 are structurally designed of proper proportions and weight to serve directly as the driving ram.

The steam cycle used in driving this hammer ispreferably, as above stated, the same as that disclosed in said Smith patent. A steam inlet passage 23 is provided in the wall of hammer body 10 and is located so as to permit passage of steam therethrough into the space B formed between the upper and lower pistons 17 and 20. As inthe case of double piston differential hammers heretofore used, the arrangement of valves is such that the steam supply is constantly connected to this space B, whereas steam pressure is supplied to the space A above the large upper piston only during the greater part of the down stroke and momentarily during the final part of the up stroke so as to cushion the final upper movement. That is, just before the moment of impact, the steam pressure in the space above the upper piston is released and. a passage from this space remains-open to exhaust until the up stroke is nearly completed, whereupon pressure is again admitted above the piston 17 so as to cushionand stop the up stroke. Admission of the fluid pressure above the upper piston thereafter is continued and acts with the aid of gravity to promptly force the piston assembly down again, the active and effective piston area then being equivalent to the area of piston 20. Thatto pressure on the upper side and will be effective together with gravity in causing the down stroke, since the under side of piston 20 is not under pressure.

The sliding valve assembly herein provided to accomplish this steam cycle will now be described. In the embodiment seen in Figs. 1 and 2, the upper piston 17 is provided with vertically extending bores 24 and 25 in which are slidably disposed tubular valves 26 and 27. These valves are comprised of hollow valve tubes 28 and 29, having end closure plugs 30, 31, 32 and 33 and side wall ports 34, 35, 36 and 37 near their upper and lower extremities. Toward their lower ends, the piston bores 24 and 25 are enlarged as at 3'8 and 39 and horizontally extending passageways 40 and 41, located in the piston 17, connect said enlarged portions of these bores with a vertical hollow passage 42 extending downwardly through the interior of piston rod 18 to a point below small piston portion 20 to a horizontally extending passage 43 which in turn communicates with a cylinder exhaust port 44.

The operation of these sliding valves during the steam cycle will now be explained. With the differential piston and sliding valves in the positions shown in Fig. l, steam is admitted to the space B between the upper and lower pistons. In this position communication between space B and the space A above the large piston is shut off since the ports 36 and 37 are telescoped within the piston bores 24 and 25. However, since these same ports 36 and 37 are in registry with the enlarged bore portions 38 and 39, space A is in communication with the steam exhaust ports 44 via ports 34 and 35 of the valve tubes, the hollow interior of said valve tubes 28 and 29, ports 36 and 37, enlarged bore spaces 38 and 39, horizontal passages 40 and 41, vertical passage 42 and horizontal passages as at 43. The steam as it enters space B will act upon the under surface of piston 17, thereby forcing that member upwardly in its cylinder in the manner above described. During this upward travel of piston 17, the valve tubes 28 and 29 are held stationary relative to the piston by means of split friction rings 47, 48, 49 and 50 which will be described in more detail hereinafter and in this position the exhaustion of steam is permitted from space A above the piston through the piston 17 and piston rod 18 to the exhaust. As this upward travel of piston 17 continues, the upper end closure plugs 30 and 31 of valve tubes 28 and 29 strike the under surface of cylinder head 14 and thus the upward travel of the valves 26 and 27 is halted while that of piston 17 continues, thereby causing relative sliding between valves and pistons. The piston 17 will continue to move upward relative to the now stationary valves until valve tube ports 36 and 37 are positioned within the space B below piston 17, thereby permitting the steam under pressure in space B to pass through the large piston 17 via these ports 36 and 37, valve tubes 28 and 29 and ports 34 and 35 to the space A above the piston. This position of the valves is seen in Fig. 2 and will be reached just prior to the end of the upward stroke of piston 17. With the valves in this position, it is clear from Fig. 2 that communication between space A and the exhaust has been interrupted and therefore the entry of steam under pressure into this space A will serve to cushion the upward stroke of the piston and gradually, as the steam pressure in space A equalizes with that in space B, it will act upon the upper surface of piston 17 so as to start that member on its downward power stroke, as has been described above. At the end of this downward power stroke, the impact surface 21 of piston rod 18 will deliver the power blow to the cap block assembly 22 and thence to the piling. Toward the end of this downward stroke, the end closure plugs 32 and 33 of the valve tubes will strike the internal annular shoulder 12 of the hammer body 10. It should be noted here that the end closure plugs 30, 31, 32 and 33 may be formed of rubber or some other resilient material, or if metal may be provided with resilient pads so as to cushion their impact with the cylinder head and internal annular shoulder. The piston 17 will then continue its downward travel sliding relative to the now stationary valves 26 and 27 until the valve tubes 28 and 29 are again enclosed in piston bores 24 and 25 with the ports 36 and 37 again in registry with the enlarged bore portions 38 and 39. Thus communication is against established between the space A above the piston and the exhaust 44, via ports 34, 35, tubes 28 and 29, enlarged bore portions 38 and 39 and passageways 40, 41, 42, and 43. The cycle is then completed and the position of the parts corresponds once again to that shown in Fig. l. The second cycle commences immediately.

The valve tubes 28 and 29 are held relative to the piston 17 during the upward and downward travel of that member by means of split friction rings 47, 48, 49 and 50 located in recesses in the piston bores 24 and 25. Referring now to Fig. 3, it will be seen that these friction rings are comprised of two or more arcuate segments 51 and 52 which are urged together by a circular spring 55, disposed in a peripheral groove 56 formed in the outer surfaces of these segments. When these split rings are positioned in the cylinder bore recesses, encircling the valve tubes 28 and 29, it will be evident that the springs 55 will urge these rings into frictional contact with the valve tubes, thereby holding said tubes stationary relative to the piston during the normal upward and downward travel of that member. However, when the valve strikes the cylinder head 14 and internal annular shoulder 12 at the end of the upward and downward strokes, respectively, these rings will permit relative sliding movement between the valve tubes and the piston.

In the embodiment of the invention shown in Figs. 4 and 5 a difierential power hammer substantially identical with that seen in Figs. 1 and 2, with the exception of the sliding valve assembly, is disclosed. This embodiment comprises a hammer body 70, a relatively large upper cylinder 72, a cylinder head 73, a relatively smaller lower cylinder 74, a combined difierential piston and ram assembly 75 having a large piston 76 and a small piston 77 interconnected by piston rod 78 and a valve assembly 79 slidably disposed in said large piston 76. This valve assembly comprises a pair of hollow valve tubes 80 and 81 which are slidably disposed in piston bores 82 and 83. The lower ends of these tubes are closed by means of plugs 84 and 85, while the upper ends 86 and 87 of the tubes are open. These tubes 80 and 81 are provided with side wall ports 88 and 89 located close to their lower plugged ends. A rigid brace 90 interconnects the valve tubes at their upper ends 86 and 87. Mounted on the under side of this brace 90 is a closure element 91 which is aligned with a central hollow passage 92 which extends vertically through large piston 76, piston rod 78 and small piston 77 into communication with a horizontal passage 93 which leads to steam exhaust ports 94. A spring 110 is mounted on the under side of the cylinder head 73 in alignment with said connecting brace 90 so as to be in position to intercept that brace during the upward travel of the differential piston and act as a cushioning means therefor. Springs 99 and 100 are mounted on the end plugs 84, 85 of the valve tubes 80 and 81, respectively, and are in alignment with an annular internal shoulder 101 formed in the hammer body at the lower end of cylinder 72. These springs serve to cushion the impact between this shoulder and the valve tubes at the lower end of the pistons downward stroke. It is of course within the purview of this invention to locate these springs fixed to the internal shoulder rather than the valve tubes and, similarly, to mount spring 110 on the brace 90. Friction split rings 102, 103, 104 and 105 are suitably disposed in the piston bores 82 and 83 so as to frictionally engage the valve tubes 80 and 81 in the manner above described in connection with the embodiment of Figs. 1 and 2.

The operating cycle of the embodiment of the invention seen in Figs. 4 and 5 is the same as that described in corn nection with the embodiment of Figs. 1 and 2. in that cycle, valve assembly 79 operates as follows: As seen in Fig. 4, the difierential piston has just completed its downward stroke and is beginning to travel upwardly. Steam under pressure is supplied through cylinder port 104 into the space B below the large piston 76. With the valve tubes in the position shown the ports 88 and 89 are telescoped within piston bores 82 and 83 and thus communication between space E and A is blocked. The piston 76 will therefor be forced upwardly and the steam contained in space A above that piston will travel through passages 92 and 93 to exhaust 94. As the piston approaches the upward end of its stroke, brace 99 will strike spring 110, which gradually will check the upward travel of brace 90, While the piston 76 will continue its upward travel, thus causing relative sliding between piston and valve tubes. This movement continues until, as seen in Fig. 5, side wall ports 88 and 89 of the valve tubes are positioned within space B below the large piston, and closure element 91 is seated on the upper surface'of piston 76 thereby blocking ofi" passage 92. Communication between space A and the exhaust will then be interrupted and steam under pressure will pass from space B through the ports 88 and 89, the hollow valve tubes 80 and 81 and their open ends 86 and 87 into the space A above the pistons, thereby cushioning the end of the upward stroke of that piston and starting. it downward on its next power stroke. As the piston approaches the end of this power stroke, spring 99 and 100 will engage Q the annular shoulder 101 and gradually urge the valve tubes and closure element 91 back into the positions hown in Fig. 4, thereby rendering the: differential piston in position to commence its next cycle.

The above described valve arrangement may also readily be substituted for the valve means in, a hammer; having a cylinder and piston means and other features constructed and proportioned as shown in said Smith Patent No. 2,598,455. The construction will then be especially well adapted for use in pile cores and with ram arrangements such as shown in that patent.

Although certain particular embodiments of the invention are herein disclosed for purposes of explanation, various further modifications thereof, after study of this specification, will be apparent to those skilled in the art to which the invention pertains. Reference should accordingly be had to the appended claims in determining the scope of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. In a differential piston fluid actuated power hammer, the combination of upper and lower pistons contained respectively in relatively large and smaller cylinders, said pistons being interconnected by a rod fluid pressure inlet means for continuously supplying fluid pressure to a space between said pistons, passage means in said upper piston communicating with the cylinder exhaust, hollow tubular valve means extending through the upper piston in slidable relation therewith and provided with ports near the upper and lower ends thereof, friction means normally holding the valve means stationary relative to the piston, said valve means projecting beyond the upper and lower surfaces of said piston, whereby contact between said valve means and the cylinder occurs near the limits of the upward and downward strokes of the upper piston thereby causing relative sliding between said valve means and the valve means being positioned relative to the upper piston during the latter part of the upstroke and the greater part of the downstroke of the piston assembly with said ports being disposed in the spaces, respectively, between the pistons and the upper piston, thereby permitting communication of fluid pressure from the former space through the hollow valve means to the latter space, and being positioned during the remainder of the operative cycle with the port near its lower end enclosed within the upper piston, thereby blocking off comm-unicat'ion between the spaces between pistons and the space above the upper piston, said port in this position being in communication withsaid passage means in the upper piston, thereby providing communication of fluid pressure from the space above the upper piston through the hollow valve means and the passage means in the exhaust.

2. A differential piston fluid actuated power hammer having interconnected upper and lower pistons contained respectively in relatively large and smaller cylinders, fluid pressure inlet means for maintaining a substantially constant pressure in a space between said pistons during the entire operative cycle of the hammer, a sliding valve assembly carried by said upper piston and comprising a plurality of hollow valve tubes provided with ports near the upper and lower ends thereof, said valve tubes being slidably disposed in bores in said piston, said bores having enlarged portions adapted to register with the lower ports of the valve tubes when said tubes are in one position, and passage means in the upper piston leading between the enlarged portions of the bores to the cylinder exhaust, thereby permitting communication of fluid pressure from the space above the upper piston to the exhaust when the lower ports and enlarged bore portions are in registry, said valve tubes projecting beyond the upper and lower surfaces of the upper piston whereby upon contact with the large cylinder near the end of the upstroke of the piston said valve tubes are caused to slide relative to the piston thereby establishing communication of fluid pressure from the space between the pistons through the valve tubes to the space above the-upper piston.

3.. In a difierentialpiston fluid actuated power hammer the combination of interconnected upper and lower pistons. contained respectively in relatively large and smaller cylinders, fluid pressure inlet means for continuously supplying fluidpressure to'ra space between said pistons, passage means extending through said upper piston and communicating with the cylinder exhaust, a plurality of hollow valve tubes provided with means near their upper and lower ends to permit the passage of fluid therethrough, said valve tubes extending through the upper piston in slidable relation therewith for projecting beyond the upper and lower surfaces thereof, means interconnecting said tubes at their upper ends provided with a closure element aligned with the passage means in the upper piston, whereby said valve tubes contact the cylinder near the ends of the upward and downward strokes of the upper piston and are thereby caused to slide relative to said piston to alternately permit communication of fluid pressure from the space between the pistons through the upper piston to the space thereabove, and communication of fluid pressure from the space above the upper piston to the exhaust.

4. In a diiferential piston fluid actuated power hammer the combination of interconnected upper and lower pistons contained respectively in relatively large and smaller cylinders, fluid pressure inlet means for continuously supplying fluid pressure to a space between said pistons, passage means extending through said upper piston and cornmunicating with the cylinder exhaust, a plurality of hollow valve tubes provided with means near their upper and lower ends to permit the passage of fluid therethrough, said valve tubes extending through the upper piston in slidable relation therewith for projecting beyond the upper and lower surfaces thereof, means interconnecting said tubes at their upper ends provided with a closure element aligned with the passage means in the upper piston, shock absorbing means carried on the lower ends of said valve tubes and shock absorbing means carried by the upper end of the large cylinder in line with the valve tube interconnecting means, whereby said valve tubes contact the cylinder near the ends of the upward and downward strokes of the upper piston and are thereby caused to slide relative to said piston to alternately permit communication of fluid pressure from the space between the '7 pistons through the upper piston to the space thereabove, and communication of fluid pressure from the space above the upper piston to the exhaust.

5. A differential piston, fluid actuated power hammer comprising a relatively large upper cylinder, a smaller lower cylinder, relatively large and small diameter pistons disposed respectively in each of said cylinders, a rod interconnecting said pistons and being of reduced diameter so as to provide a space therebetween, fluid pressure inlet means for maintaining a substantially constant pressure in said space during the entire operative cycle of the hammer, hollow tubular valve means extending through the upper piston and slidable relative thereto upon contact with the cylinder near the end of the upward and downward strokes of the hammer, said valve means being radially offset from the connecting rod and having fluid passing apertures near each end, the valve means being positioned relative to the upper piston during the latter part of the upstroke and the greater part of the downstroke of the piston assembly with its fluid passing apertures disposed, respectively, in the spaces between the pistons and above the upper piston, thereby permitting fluid pressure communication from the former to the latter, and being positioned during the remainder of the operative cycle with the fluid passing aperture near its lower end enclosed within the upper piston, thereby blocking off communication between the space between pistons and the space above the upper piston, and passage means in said upper piston extending through said interconnecting rod and lower piston and cooperating with said valve means to provide communication between the space above the upper piston and the exhaust only when the valve means is in the latter position.

6. A differential piston, fluid actuated power hammer having upper and lower pistons interconnected by a piston rod and contained, respectively, in relatively large and smaller cylinders, fluid pressure inlet means for maintaining a substantially constant pressure in a space between said pistons throughout the entire operative cycle of the hammer, sliding valve means carried by said upper piston and being radially offset from said connecting rod, the ends of said valve means projected beyond the faces of the upper piston, whereby the valve means is adapted to be shifted relative to the upper piston upon contact of its ends with the cylinder near the limits of the upward and downward strokes of the piston, fluid port means provided near the lower end of said valve means and being in continuous open communication through the valve means with the space above the upper piston, the valve means being positioned relative to the upper piston during the latter part of the upstroke and the greater part of the downstroke thereof with said port means being disposed beneath said piston in the space between pistons, thereby providing fluid pressure communication from the space between pistons to the space above the upper piston, and being positioned during the remainder of the operative cycle with said port means enclosed within the upper piston, thereby blocking off communication between the space between pistons and the space above the upper piston, and passage means located in said upper piston and extending through the piston rod to a cylinder exhaust passage, said passage means and valve means cooperating to provide communication between the space above the upper piston and the exhaust only when the valve assembly is in the latter position.

References Cited in the tile of this patent UNITED STATES PATENTS 682,492 Payton Sept. 10, 1901 685,563 Botts Oct. 29, 1901 1,241,783 Tocknell Oct. 2, 1917 2,598,455 Smith May 27, 1952 

